Power density in plasma processing equipment, such as those designed to perform plasma etching of microelectronic devices and the like, is increasing with the advancement in fabrication techniques. For example, powers of 5 to 10 kilowatts are now in use for 300 mm substrates. With the increased power densities, enhanced cooling of a chuck, such as an electrostatic chuck (ESC) is beneficial during processing to control the temperature of a workpiece (wafer) uniformly.
ESC cooling bases designed for extreme thermal uniformity, specifically in the azimuthal direction that include multi-zone ESC heater control allow for the widest process window possible under various process and plasma conditions. Individual heater zones in the radial direction can compensate for minor radial non-uniformities that may be present. Such a design however does not allow for any independent azimuthal temperature control, specifically around the wafer edge. Although some processes require extreme azimuthal temperature uniformity, other processes may require more flexibility of the edge temperature as a function of azimuth angle.